1 files changed, 170 insertions, 0 deletions
diff --git a/src/shared/qtlockedfile/qtlockedfile_win.cpp b/src/shared/qtlockedfile/qtlockedfile_win.cpp
new file mode 100644
index 0000000000..2f35635b55
--- /dev/null
+++ b/src/shared/qtlockedfile/qtlockedfile_win.cpp
@@ -0,0 +1,170 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include "qtlockedfile.h"
+
+#include <qt_windows.h>
+#include <QFileInfo>
+
+namespace SharedTools {
+
+#define SEMAPHORE_PREFIX "QtLockedFile semaphore "
+#define MUTEX_PREFIX "QtLockedFile mutex "
+#define SEMAPHORE_MAX 100
+
+static QString errorCodeToString(DWORD errorCode)
+{
+    QString result;
+    char *data = 0;
+    FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
+                    0, errorCode, 0,
+                    (char*)&data, 0, 0);
+    result = QString::fromLocal8Bit(data);
+    if (data != 0)
+        LocalFree(data);
+
+    if (result.endsWith(QLatin1Char('\n')))
+        result.truncate(result.length() - 1);
+
+    return result;
+}
+
+bool QtLockedFile::lock(LockMode mode, bool block)
+{
+    if (!isOpen()) {
+        qWarning("QtLockedFile::lock(): file is not opened");
+        return false;
+    }
+
+    if (mode == m_lock_mode)
+        return true;
+
+    if (m_lock_mode != 0)
+        unlock();
+
+    if (m_semaphore_hnd == 0) {
+        QFileInfo fi(*this);
+        QString sem_name = QString::fromLatin1(SEMAPHORE_PREFIX)
+                           + fi.absoluteFilePath().toLower();
+
+        m_semaphore_hnd = CreateSemaphoreW(0, SEMAPHORE_MAX, SEMAPHORE_MAX,
+                                           (TCHAR*)sem_name.utf16());
+
+        if (m_semaphore_hnd == 0) {
+            qWarning("QtLockedFile::lock(): CreateSemaphore: %s",
+                     errorCodeToString(GetLastError()).toLatin1().constData());
+            return false;
+        }
+    }
+
+    bool gotMutex = false;
+    int decrement;
+    if (mode == ReadLock) {
+        decrement = 1;
+    } else {
+        decrement = SEMAPHORE_MAX;
+        if (m_mutex_hnd == 0) {
+            QFileInfo fi(*this);
+            QString mut_name = QString::fromLatin1(MUTEX_PREFIX)
+                               + fi.absoluteFilePath().toLower();
+
+            m_mutex_hnd = CreateMutexW(NULL, FALSE, (TCHAR*)mut_name.utf16());
+
+            if (m_mutex_hnd == 0) {
+                qWarning("QtLockedFile::lock(): CreateMutex: %s",
+                         errorCodeToString(GetLastError()).toLatin1().constData());
+                return false;
+            }
+        }
+        DWORD res = WaitForSingleObject(m_mutex_hnd, block ? INFINITE : 0);
+        if (res == WAIT_TIMEOUT)
+            return false;
+        if (res == WAIT_FAILED) {
+            qWarning("QtLockedFile::lock(): WaitForSingleObject (mutex): %s",
+                     errorCodeToString(GetLastError()).toLatin1().constData());
+            return false;
+        }
+        gotMutex = true;
+    }
+
+    for (int i = 0; i < decrement; ++i) {
+        DWORD res = WaitForSingleObject(m_semaphore_hnd, block ? INFINITE : 0);
+        if (res == WAIT_TIMEOUT) {
+            if (i) {
+                // A failed nonblocking rw locking. Undo changes to semaphore.
+                if (ReleaseSemaphore(m_semaphore_hnd, i, NULL) == 0) {
+                    qWarning("QtLockedFile::unlock(): ReleaseSemaphore: %s",
+                             errorCodeToString(GetLastError()).toLatin1().constData());
+                    // Fall through
+                }
+            }
+            if (gotMutex)
+                ReleaseMutex(m_mutex_hnd);
+            return false;
+	}
+        if (res != WAIT_OBJECT_0) {
+            if (gotMutex)
+                ReleaseMutex(m_mutex_hnd);
+            qWarning("QtLockedFile::lock(): WaitForSingleObject (semaphore): %s",
+                        errorCodeToString(GetLastError()).toLatin1().constData());
+            return false;
+        }
+    }
+
+    m_lock_mode = mode;
+    if (gotMutex)
+        ReleaseMutex(m_mutex_hnd);
+    return true;
+}
+
+bool QtLockedFile::unlock()
+{
+    if (!isOpen()) {
+        qWarning("QtLockedFile::unlock(): file is not opened");
+        return false;
+    }
+
+    if (!isLocked())
+        return true;
+
+    int increment;
+    if (m_lock_mode == ReadLock)
+        increment = 1;
+    else
+        increment = SEMAPHORE_MAX;
+
+    DWORD ret = ReleaseSemaphore(m_semaphore_hnd, increment, 0);
+    if (ret == 0) {
+        qWarning("QtLockedFile::unlock(): ReleaseSemaphore: %s",
+                    errorCodeToString(GetLastError()).toLatin1().constData());
+        return false;
+    }
+
+    m_lock_mode = QtLockedFile::NoLock;
+    remove();
+    return true;
+}
+
+QtLockedFile::~QtLockedFile()
+{
+    if (isOpen())
+        unlock();
+    if (m_mutex_hnd != 0) {
+        DWORD ret = CloseHandle(m_mutex_hnd);
+        if (ret == 0) {
+            qWarning("QtLockedFile::~QtLockedFile(): CloseHandle (mutex): %s",
+                        errorCodeToString(GetLastError()).toLatin1().constData());
+        }
+        m_mutex_hnd = 0;
+    }
+    if (m_semaphore_hnd != 0) {
+        DWORD ret = CloseHandle(m_semaphore_hnd);
+        if (ret == 0) {
+            qWarning("QtLockedFile::~QtLockedFile(): CloseHandle (semaphore): %s",
+                        errorCodeToString(GetLastError()).toLatin1().constData());
+        }
+        m_semaphore_hnd = 0;
+    }
+}
+
+} // namespace SharedTools